Treated seeds

ABSTRACT

A method of treating primed seeds which results in a prolongation of shelf life compared to optionally dried conventionally primed seeds of the same species having substantially the same moisture content (MC), wherein the primed seeds are subjected to a water stress, a heat treatment or a combination thereof and are subsequently—where desired—dried back to a desired MC and seeds obtainable by such a method.

This application is a continuation of Ser. No. 08/667,167 filed Jun. 20,1996 (U.S. Pat. No. 6,313,377); which is a continuation of Ser. No.08/395,348 filed Feb. 28, 1995 (abandoned).

The present invention relates to treated primed seeds having a longershelf life than conventionally primed seeds, a process for obtainingsuch seeds and plants derived therefrom.

Primed seeds and methods for obtaining them are known in the art.

Primed seeds are generally capable of a faster germination over time anddisplay better synchronization in germination, than non-primed seeds.

Conventional seed priming processes are i.a. disclosed by EP 309 511 B1and EP 254 569 B1.

The present invention provides a method of treating primed seeds whichresults in a prolongation of shelf life compared to optionally driedback conventionally primed seeds of the same species havingsubstantially the same moisture content (MC) characterised in that theprimed seeds arc subjected to a water stress, a heat treatment or acombination thereof and are subsequently—where desired—dried back to adesired MC.

The drying back of the seeds as abovementioned, involves a reduction inthe seed MC. The drying back may be to any desired MC. In a preferredembodiment the drying back is to a MC of untreated seeds, i.e. dry seedswhich have not been primed.

Hereinafter the terms MC and water content will be used interchangeably.The MC will be given in percentage terms, based on seed freshweight(unless otherwise stated).

The water stress may be achieved by any manner known in the art whichwill result in the seeds having a lower MC.

In general a water stress will be obtained by reduction of the MC ofconventionally primed seeds by 5% units or more, i.e. to 20% or less, ifthe conventionally primed seeds have an initial MC of 25%, or to 50% orless if the conventionally primed seeds have an initial MC of 55%. Morespecifically, the water stress will in general be achieved by reductionof the MC by 5% units up to 20% units, whereby, it is in generaladvantageous not to reduce the MC to a value below 15%

The water stress should be maintained for a longer period of time, ingeneral 1 to 7 days, depending i.a. on the temperature, whereby theoptimum conditions will depend on the seed species and can be determinedby standard tests. It will be appreciated that this can be achieved bymaintenance of the MC of the conventionally primed seeds constant at thedesired reduced level (i.e. conveniently 5 to 20% units below the MC ofconventionally primed seeds) or by drying the conventionally primedseeds slowly enough for them to remain sufficiently long under waterstress.

Accordingly prolonged shelflife may be attained by incubation of theprimed seeds at a water potential which induces a water stress, by slowMC reduction of primed seeds, by an initial quick MC reduction of primedseeds up to a MC where the seeds are still subject to water stress,followed by incubation or slow MC reduction of the thus obtained partlydried primed seeds or by a heat shock. Slow MC reduction can be achievedin a manner known per se, e.g. by drying under mild conditions or bybringing the primed seeds in contact with an osmoticum that is not toxicto the seeds and having a water potential below O MPa. The descriptionof processes (a), (b) and (c) hereinafter, illustrates typicalconditions for subjecting primed seeds to a water stress.

The water stress may be achieved by:

a) slowly drying primed seeds at a temperature of from 3 to 40° C. for 3to 7 days, or

b) reducing the MC of primed seeds under conventional drying conditionsby 5 to 20% units and storing the thus dried seeds for 1 to 7 days in acontainer with minimal air and moisture exchange, at a temperature offrom 3 to 40° C. or

c) incubating primed seeds in an osmoticum for 1 to 7 days at a waterpotential chosen to reduce the MC of the primed seeds by 5 to 20% units.

The heat treatment may be achieved by subjecting primed seeds to a heatshock in the range of from 25 to 45° C. for from about 1 to 5 hours.

The seeds produced according to the processes of the invention, havegreater desiccation tolerant embryos than conventionally primed seeds,in that the former survive longer storage periods under ambient storageconditions as hereinafter defined.

By a seed comprising a desiccation tolerant embryo is meant a seed inwhich a reduction the MC of the seed to a value typical for dehydratedseeds e.g. of about 5 to 7%, does not substantially adversely affect theseeds viability, the viability being measured in terms of ability togerminate when placed under suitable growing conditions or after anappropriate standard test, e.g. a controlled deterioration test (seehereinafter) either before or after a prolonged storage period atambient storage conditions.

The embryo of the seed is taken to mean structures which are necessaryfor the development of the seed, such as the cotyledon, axis andnon-emerged radicle tip and which collectively or in part are able toacquire a desiccation tolerance.

Primed seeds can be stored for a number of weeks at about 5° C. but areunsuitable for storing for extended periods of time under ambientstorage conditions.

By the term primed seed is meant (insofar as not otherwise stated), thatthe seed has been subjected to conventional priming techniques ashereinafter discussed, it has a MC in the range of from 20 to 55%(depending on species) and has a desiccation tolerance typical ofconventionally primed seed. It will be appreciated that all non-primedseed is desiccation tolerant i.e can survive drying, the extent ofdesiccation tolerance being species dependent. On priming according toconventional processes, the seed becomes less desiccation tolerant, theloss in desiccation tolerance increasing with the increase in period ofpriming, until a point at which the seed can no longer be said to bedesiccation tolerant, this complete loss of desiccation toleranceoccurring at the point of germination of the seed. The processes of thepresent invention, as hereinafter described, are applied tonon-germinated seed which has been primed according to conventionalpriming processes. Non-germinated seed is defined herein as seed inwhich the radicle and/or hypocotyl has not protruded or emerged from theseed coat or pericarp. The radicle and/or hypocotyl may have caused theseed coat to split or crack, however it will not have protruded throughthe split or crack. The endosperm surrounding the embryo, may be visiblethrough the split or crack. Non-germinated conventionally primed seed towhich the proceeses of the present invention have been applied, willhereinafter be referred to as as treated seed(s). Non-germinatedconventionally primed seed(s) to which the processes of the presentinvention have not been applied, will hereinafter be referred to asconventionally primed seed(s). Commercially acceptable seed(s) whichhave not been primed, shall be referred to as untreated seed(s).

It is also possible to determine the stage of the germination process byphysical parameters, e.g. size, volume or density. In this way, aselection can be made of seeds to be treated according to the invention.

Thus as is demonstrated below, treated seed has a longer shelf life thanconventionally primed seed of the same species and MC. The longer shelflife can be demonstrated by measuring % germination under the same orsimilar conditions e.g standard growing conditions (as below defined),after either a controlled deterioration test, or storage under ambientconditions; the treated seed having higher % germination of normalplants compared to conventionally primed seed which have been subjectedto the same controlled deterioration test or storage conditions.

By standard growing conditions is meant a temperature in the range ofabout 15 to 20° C. in the presence of air and water.

The term shelf life as used herein may be expressed in terms ofviability (i.e. in terms of ability to germinate and give rise to normalplants after storage under ambient storage conditions, for example aftersubjection to a controlled deterioration (CD) test (Tarquis A. M. &Bradford K. J., J. Exptal. Bot. Vol. 43, 1982, No. 248,pp. 307-317). Theviability of seeds subjected to the CD-test may be determined inlaboratory tests according to International Rules (ISTA, 1976).Differences between CD test results generally correlate with differencesin shelf storage life after storage under ambient storage conditions.

Typical examples of conventional priming methods include treatment ofseeds with an osmoticum (as disclosed i.a. by Heydecker, andmodifications thereof, such as for example the Drum Priming Method),treatment with water in a solid matrix (as disclosed i.a. in EP 309 551B1) etc.

By the term “ambient storage conditions” is meant storage at ambienttemperature and relative humidity (RH).

The term “ambient temperature” as used herein, refers to a temperaturefrom about 3° C. to about 25° C. By the term “ambient RH” is meant a RHin the range of from about 20% to about 90%.

Application of the processes (a), (b) or (c) of the invention ashereinbelow described, involves a reduction in seed MC.

Process (a) of the invention involves a slow rate of water loss ofprimed seeds(hereinafter referred to as slow drying). Thus, the primedseeds are subjected to an incubation phase in which the rate of waterloss is maintained within the range of from about 0.1% and 1.0% of dryweight of the seed hour⁻¹, preferably within about 0.2% to about 0.4%h⁻¹. Slow drying can be performed in a drum (drum priming), oxygenatedgas or oxygen being actively supplied or air may enter the system(passive conditions) simply, by mixing. The rate of water loss isdetermined by weighing seeds after different periods of incubation andplotting seed weight over time. It will be appreciated that the rate ofmoisture loss required to induce long shelf life will vary, from speciesto species, within the above defined range. Seeds held under suchconditions will have a final MC of between about 5% to about 20%,generally from about 5% to about 15%, lower than that of the primedseeds.

In slow drying, the seeds can be incubated at any temperature between 3°C. up to about 40° C. Preferably, seeds are incubated at temperaturesfrom about 20° C. to about 35° C. The incubation period lasts for about24 hours up to about a week or more depending on incubation temperature.Thus e.g. the incubation period may be from about 24 hours up to about 3days or more, at a temperature of 20° C., depending on seed type, or itmay be for up to a week or more at a lower temperature, such as 8° C.,depending on seed type. Lower temperatures can be employed, for example,to minimise the risk of infestation with pathogens.

According to process (b), hereinafter referred to as moist storage,primed seeds are incubated at a seed MC which is lower than the seed MCof primed seeds. Thus the MC of primed seeds is reduced (by drving underconventional drying conditions e.g. “fast drying conditions”), bybetween 3 to 20% units, preferably between 5% and 15% units, over aperiod of less than 24 h. such as 8 h or less. The minimum value MC towhich the seeds are dried is about 15%. Thereafter the so dried seedsare subjected to a water stress by incubation in a container withminimal air and moisture exchange, the temperature and length ofincubation being a, for slow drying above.

The term conventional drying conditions as used in connection withprocess (b) hereinabove (and where used hereinbelow) refer toconventional drying conditions e.g. drying back by means of a high speedair flow at ambient temperature as known in the art and generallyapplied for the drying of conventionally primed seeds.

A further method of subjecting primed seeds to a water stress, theincubation process according to process (c) of the present invention,comprises a PEG (or other suitable osmoticum solution) treatment, whichinvolves a reduction in the seed MC of seeds which have been subjectedto a priming step by incubation in solutions, the water potential ofwhich is less than O MPa. During incubation seed water content is slowlyreduced by between 3 to 20% units, as described for process (b), bykeeping the osmotic potential of the solution at a specified value,within the range of from about −0.5 to about −4.0 MPa. In this state theseeds experience a mild water stress due to a lack of availability offree water. Incubation preferably takes place in a water column (liquidincubation), preferably under aerated conditions. It can also take placeby placing the primed seeds on filter paper saturated in an osmoticumsolution.

Suitable incubation conditions (length, temperature) for process (b) and(c) include i.a. the conditions as described for process (a).

The incubation according to process (c) will typically be carried out inan osmoticum having a water potential that is low enough to withdrawwater from the primed seeds. Any suitable osmoticum which does not harmthe seeds, can be used e.g. polyethylene glycol (PEG) solutions such asPEG 8000 (British Petroleum). Typically, the seeds are contacted with asolution such as PEG 8000, mannitol, or a salt solution such as NaCl orthe like. The osmotic potential should be such, that the seed MC is heldat a sufficiently low level so that the induction of desiccationtolerance occurs.

Plant growth regulators may be added to the osmoticum solution at aconcentration of between about 10⁻² M and 10⁻⁸ M in the firstincubation. Suitable regulators include giberellins, abscisic acid(ABA), and auxins such as indole butyric acid (IBA).

In incubation in a water column, the amount of seed per unit volumesolution, can be from 1-200 g seeds 1⁻¹. Preferably, the seeds arepresent at about 25 g seeds 1⁻¹. Generally, the incubation may be forseveral days, extending to weeks or longer. After incubation, the seedsare washed in water.

With incubation on filter paper, the paper is moistened with a suitableosmoticum (as above described). Generally, seeds imbibed and primed to aMC of between about 25% and 55%, can be laid onto the moistened filterpaper in a closed system, having a high RH eg 100%, the temperature andcontact time being as above described).

Where desired the MC of primed seeds can be reduced by e.g. about 10%units by fast drying, before incubation in an osmoticum as abovedescribed. Such a step is not however essential.

In the heat treatment, the primed seeds are subjected to a heat shock inthe range of about 25 to 45° C., preferably in the range of 35 to 40°C., for periods of time in the range of from about 1 to about 5 h.Preferably the MC of seed which is subjected to a heat shock is in therange of from 0 to 20% units lower than the seed MC after priming.Generally it is advantageous that the MC of the seeds which aresubjected to a heat shock, is not lower than 15%. The heat shock may beapplied by any known suitable method. Thus suitably the seeds may beplaced in a container which is then placed in an incubator.

It will be appreciated that the desired result (primed seeds having along shelf life), may also be attained by a combination of water-stressand heat-stress i.e. a combination of heat shock with either process(a), (b) or (c).

The optimum process and optimum conditions for the above mentionedprocess (a) to (c) and the heat shock for a given seed species, may beestablished by determining the shelf life potential and germination rate(t₅₀) in as ma known per se.

Treatment of primed seeds according to any of the processes (a) to (c),the heat shock or a combination of such processes as above described,and subsequently—where desired—drying the seeds back to a desired MC,gives rise to seeds having a longer shelf life than conventionallyprimed seeds of the same species having substantially the same MC.

The invention therefore provides seeds obtainable by process (a), (b),(c), the heat shock or a combination of such processes as abovedescribed, the seeds subsequently—where desired—being drying back to adesired MC.

The present invention also provides treated primed seeds in wet or dryform, having a shelf life, when stored under ambient storage conditions,which is substantially longer than that of conventionally primed seedsof the same species having substantially the same MC and of which the MChas optionally been reduced under conventional drying conditions.

The seeds of the invention have a MC within the range of that typicalfor dry i.e untreated seeds, up to a MC at which metabolic processesother than germinative metabolic processes continue.

Typical commercial forms of the seeds of the invention include seedshaving a MC in the range of from more than 15% to about 55%,(hereinafter referred to as wet seeds of the invention) and seeds thathave been dried back to roughly the MC of dry seeds, i.e. having a MC inthe range of from about 2% to about 15% of seeds (hereinafter dry seedsof the inventions).

Dry seeds of the invention are obtained by drying back seeds obtainedaccording to any one processes (a), (b), (c), a heat shock, acombination of either (a), (b) or (c) with a heat shock, according tothe invention, to a final MC of the order of that of non-germinated,non-primed seeds (i.e. the untreated seeds) using conventional i.e. fastdrying conditions. Under conventional drying conditions, seeds can bedried back at a temperature lying within the range of from 10° C. to 50°C. generally from 20° C. to about 35° C., at a relative humidity withinthe range of from 30% to 90%, generally from 30% to about 50%, in stillair or in flowing air at speeds typical for drying back seeds. Forexample, the airflow speed may be at any speed up to 2 m s⁻¹ or faster.The period of time may be for any suitable time interval up to 24 hours,depending on drying conditions employed. Suitable conventional dryingconditions include, for example, temperature of 20° C., a relativehumidity of 40% in air flowing at a speed of 2 m s⁻¹ over 16 hours.

The dry seeds of the invention are useful, in that their germinationrate is substantially shorter than that of untreated seeds of the samespecies. The germination rate is typically expressed in terms of t₅₀,i.e. the time by which 50% seeds of a seed sample germinate.

The wet seeds of the invention are useful, i.a. in that they can bedried back to dry seeds of the invention in conventional manner.

The—dry and wet—seeds of the invention have furthermore the advantagethat they have a substantially longer shelf life than conventionallyprimed seeds of the same species having substantially the same MC.

The invention accordingly provides non-germinated seeds having a MC inthe range of from 2 to 55% characterized in that said seeds when havinga MC of untreated seeds, or after having been dried back to such a MCunder conventional drying conditions, have a t₅₀ which is substantiallyshorter than that of untreated seeds of the same species. Suitably thet₅₀ is 60% or less than that of untreated seeds of the same species.Preferably the t₅₀ is 50% or less, more preferably less than 40%. The MCof untreated seeds is generally in the range of from 2 to 15%. The t₅₀of the dry seed of the invention is generally substantially the same asthe t₅₀ of conventionally primed seed of the same species havingsubstantially the same MC.

The t₅₀ may be determined in a conventional manner e.g. according to themethod of Orchard T. G. ( 19771 ) Seed Sci. & Technol. Vol 5, pp. 61-69.Generally such a determination is carried out at a temperature in therange of from about 15 to 20° C. on e.g water saturated filter paper.

The invention further provides treated primed seeds in wet or dry formhaving a shelf life when stored at ambient storage conditions which issubstantially longer than that of conventionally primed seeds in eitherwet form or after having been subjected to conventional dryingconditions.

The term shelf life as used herein refers to the time period (term) thatseeds can be stored under ambient conditions without substantiallylosing their ability to germinate.

The ability of seeds of the invention to germinate is accordinglysubstantially unaffected after storage over a period of time and underconditions which adversely affect the germination ability (expressiblein % normal plants germinating) of conventionally primed seeds.

For convenience, it is accepted that seeds have not substantially losttheir ability to germinate after storage, if the % of germinating plantshas not been reduced by more than 20% units, preferably less than 15%units, more preferably less than 10% units, after storage.

Thus, by the statement “seeds of the invention have a shelf life of atleast 35% longer than conventionally primed seeds” is meant that ittakes at least 35% storage time units longer for seeds of the inventionto substantially lose their germination ability (% normal plantgerminating) than conventionally primed seeds of the same species storedunder the same conditions.

Dry seeds of the invention have a shelf life which is substantiallylonger than that of conventionally primed seeds of the same species ofthe same species having substantially the same MC. Suitably the shelflife is at least 35%, more specifically at least 50% longer than that ofconventionally primed seeds of the same species when said conventionallyprimed seeds are dried back to a MC of untreated seeds under fast dryingconditions as typically employed for the drying of conventionally primedseeds. Under optimum incubation/heat treatment conditions, the shelflife may be extended by 150% and more. Typically the shelf life will beextended by 50 to 120%, and even after incubation/heat treatment underless optimized conditions, by 50 to 100%. In absolute terms, the shelflife of dry seeds of the invention will easily exceed 8 months, morespecifically 12 months, when stored under conditions typical foruntreated seeds, and extend to 24 months or longer. The dry seeds of theinvention have preferably a MC in the range of from 5% to 8%. The shelflife of the seeds of the invention, will not be longer than that ofuntreated seeds of the same species.

Suitable storage conditions for the dry seeds of the invention areambient storage conditions, for untreated seeds e.g at a relativehumidity generally of from about 20% to 90%, preferably from about 30%to 60% and a temperature of from about 3° C. to 25° C., depending on theseed type.

Appropriate shelf storage conditions for wet seeds of the invention maycomprise storage in a container with minimal air and moisture exchangeat a temperature of from about 3° C. to 10° C., depending on seed type.Under such storage conditions the seeds have a shelf life of from about4 to 6 weeks.

The seeds of the invention may be any desired seed species to which aconventional priming process can be applied. Examples of suitable seedtypes include tomatoes, peppers, melons, water melons, cucumbers,Brassicas, leeks, carrots, onions, squashes, gherkins, endives,Impatiens. Verbenas, Primulas, Pelargoniums, Viola, Chigoriums andCyclamen. Specific examples of Brassicas are cabbage, broccoli,cauliflower and Brussel sprouts.

Also encompassed within the ambit of the present invention are plantsgrown from seed as herein described.

There are a number of methods of priming seeds known in the art. Theseare briefly reviewed hereinafter:

Non-primed i.e. untreated seeds, depending on species, may be soaked upto a few hours in an aqueous solution in e.g. a water column, in apre-priming treatment. Such a pre-treatment known in the art, helpsprevent the seeds from sticking together during priming, and/or readiesthe seeds for priming.

Non-primed seeds or seeds which have undergone the aforementionedpre-priming treatment, are placed under conditions e.g. time,temperature, water uptake by seed, which enable the seed to imbibe waterto a level at which pre-germinative metabolic processes commence andcontinue but at which germination(as above defined) is not possible.

Imbibition may be carried out according to any known imbibition process.Thus for example (non-germinated) seeds to be imbibed may be placed in adrum or a water column, with or without aeration, at a water potentialof 0 MPa (if the seeds are placed in water), or between about 0 MPa toabout −1.5 MPa if the seeds are placed in an osmoticum solution.Depending on the choice of priming technique, the amount of waterimbibed is defined by the osmotic potential of the priming solution (inaqueous liquid priming techniques such as water columns) and the amountof water added to the system (for eg drum priming techniques).

The seeds imbibe added water until their MC typically rises to betweenabout 25% to about 55%, preferably to about 30% to about 50%, dependingon seed type.

MC of seeds is calculated using the formula:$\frac{{Wi} - {Wa}}{Wi} \times 100$

where

Wi=weight initial

Wa=weight after oven drving seeds at 103° C. for 16 hours or 130° C.over 2 hours.

Imbibition takes place at any temperature conducive to the up take ofwater, generally, between about 5° C. and about 30° C., depending onspecies. When imbibition takes place in a water column, the degree ofaeration should be sufficient to keep the seeds buoyed or in suspension.Imbibition can be for any suitable period up to about 24 hours,preferably from about 4 to about 10 hours depending on species. It maybe a separate step before priming or may be an integral part of priming.

For proper priming the MC of the seeds is maintained at a relativelyconstant level, ie ±1 to 3% of the desired MC, typically i.e. betweenabout 20% to about 55%, preferably between about 30% and 50%, of theseeds. Preferably, priming is carried out in a drum, for about 1 toabout 21 days, preferably from about 2 days to 15 days, typically at atemperature in the range of about 5° C. to about 30° C., preferably fromabout 15° C. to about 25° C., depending on species.

The optimum seed MC and length of the priming step, depends on theparticular seed type employed. These optimum values can be found usingconventional procedures, for example, by setting different MCs forseeds, subjecting seeds to different incubation periods under certaincontrolled conditions eg temperature, RH and aeration.

Where it is desired to add a biological to the seed, the biological maybe applied using techniques known in the art. Thus for example thebiological may be added in any suitable form e.g an inoculum whichmay/may not be in the form of a suspension of micro-organisms in asuitable medium, dry fungal spores or freeze-dried or lyophilisedbacteria. The biological may be added at any suitable stage of theprocess of the invention. Preferably it is added in the form of aninoculum at or near the beginning of the priming or alternatively inprocesses involving a treatment before priming, at or near the beginningof such pretreatment.

Suitable biologicals may be selected from the group comprisingbeneficial micro-organisms such as Bacillus. Pseudomonas, Trichodermaand Rhizobia. Particular examples of suitable micro-organisms includePseudomonas fluorescence, Pseudomonas putida, Xanthomonas maltophilia,Bacillus spp. such as Bacillus subtilis, Bacillus thuringiensis,Bacillus cereus, Trichoderma viride, Trichoderma harzarium, Trichodermakoningii, Gliocladium virens, Fusarium oxysporum(non-pathogenicisolates) and the like. The biological may be specifically chosen whereit is desired to treat a seed such that it is resistant to a particularplant pathogen e.g. Pseudomonas may be added to seed which is for sowingin soil known to be heavily infested by Pythium or Bacillus spp. may beadded to seed to be sowed in seed which is prone to attack by Alternariaspp. eg carrot.

Generally the biological should be present in the range of from 10³ to10⁹ colony forming units(cfu) seed⁻¹, depending on species of seed andbiological. Thus e.g the cfu of Rhizobia on legumes such as alfalfa,should be about 10³ seed⁻¹. However for most biologicals the cfu seed⁻¹,can be in the order of about 10⁴ to about 10⁷.

Where a seed coating is to be applied to the seed, it may be appliedbefore, after or during the incubation period and either before or afterany subsequent drying step. The coating may comprise any conventionalmaterial commonly used in seed coatings and may be added to the seedusing conventional coating or pelleting techniques. The coating maycomprise plant growth regulators such as gibberellins or auxins and/orany of the abovementioned micro-organisms such as Pseudomonas orTrichoderma and the like. Typically, the content of growth regulatorwill be in the range of from about 0.0001% to about 0.1% by weight ofthe coating material.

The coating may comprise any conventional material commonly used in theart for protecting or pelleting seed. Suitable materials include clayssuch as sub-bentonite and bentonite, vermiculite, along with additivessuch as perlite, pumice, metal stearates, polyethene, polystryrene,polyurethane, talcum powder, polypropene, polyvinyl chloride, starches,loams, sugars, arabic gums, organic polymers, celluloses, flours such aswood flours, quartz powders and the like.

Accordingly the present invention further provides seeds obtainable byany one of the abovementioned processes, the seeds being colonised withbeneficial biologicals.

In a yet further embodiment the present invention provides seedobtainable by any one of the abovementioned processes, the seed beingprovided with a protective coating which optionally has addedbiological.

Then no follow examples which further illustrate the invention. It is tobe understood that the examples are not to be viewed as limiting thescope of the invention in any way.

EXAMPLE 1 Slow Drying

6 g dry pretreated seeds of Viola are primed by being placed in a 6liter drum which is rotated on its side at a speed of 3 rpm for 3 daysin a room wherein the room temperature is controlled at 20° C. and theroom RH is controlled at 70%. The drum has a 7,5 cm diameter opening init lid, over which a cotton mesh is placed (mesh size approx. 0,1 mm),to allow for aeration of the seed. Seed MC during priming is maintainedat 35% wet weight of the seeds. Initial MC of the dry seeds isdetermined by weighing a sample of the seeds before and after ovendrying for 2 hours at 130° C. Seed dry weight is determined usingmethods known in the art. A sufficient amount of water is added to thedrum so as to bring the MC of the seeds up to the desired level, in thiscase 35% wet weight. Evaporation (1-2%, per day calculated on a freshweight basis) is monitored by weighing the drum and contents andreplenishing with water to make up any weight differences observedbetween weighing, on a daily basis.

10 g (wet weight) control primed seeds are removed from the drum after 3days and dried in flowing air (2 m/s) at a temperature of 20° C. and RHof 40% for 16 hrs. Drying rate is 5-10% moisture loss/hr calculated on adry seed weight basis. Seed MC after drying is found to be 6%.

70 g of thus primed seeds of a test sample (MC 35%) are subjected toincubation by being further incubated in the same drum for 3 days, in aroom under the following slow drying conditions of temperature, relativehumidity and rate of water loss: temperature 20° C., RH 90% and rate ofwater-loss, is 0.1-0.3% MC/hr. determined by weighing as described aboveThe drum opening is covered with a nylon mesh having a pore size ofapprox. 0,6 mm to facilitate evaporation. Seeds are then taken out ofthe drum and dried under the same conditions as for control seeds above,to a MC of 6%.

Seeds are sown on water-saturated filter paper, and incubated at 20° C.in the light. The percentage of germinated seeds is counted daily, themean time to germination t₅₀ is calculated according to the method ofOrchard T. G. (1977) Seed Sci.& Technol. Vol 5, pp 61-9.

The percentage of normal plants is determined by sowing seeds in trays,on top of a 3 cm layer of standard potting soil supplied by EGO, TheNetherlands (EGO 1 Peatsoil, pH 5,5, electrical conductivity 0.9 mS,total nitrogen content 5,1 mmol/l). The trays are covered withtransparent covers and placed in the light (10,000 lux.) at atemperature of 20° C. After 21 days seedlings are evaluated by cotyledonand hypocotyl visualization according to ISTA rules, as described in theHandbook for Seedling Evaluation supra, at page 64.

Shelf life is determined using CD tests as described in the referencecited above by Tarquis et al. 1991. For CD testing, the seed MC wasuniformly increased to 10% by incubation in 75% RH for 3 days at 20° C.The samples of seeds in equilibrium at an RH of 75% were then sealed injars that were incubated at 48° C. for 24 h. At the end of thedeterioration period, the seeds are germinated on paper at 20° C. Normalseedlings are counted after 14 days. CD results are expressed as %germination of normal plants.

Seeds are stored at 18° C., and relative humidity 30% for 9, 14 and 23months. After storage seeds are germinated on soil. Results are shown inTable 1.

TABLE 1 Data for different varieties of Viola: Soil test, directly I₅₀,directly CD-test results after treatment after treatment (24 hrs) (%germination) Variety Cont. Inv. Cont. Inv. Cont. Inv. “Roc Yellow” 1.71.7 1 73 74 78 “Roc Golden” 2.0 1.8 7 68 65 69 “Roc Blue” 2.3 2.0 0 6566 67 “Roc White” 1.5 1.3 0 52 88 84 Soil test after Soil test afterSoil test after 9 months storage 14 months storage 23 months storage (%germination) (% germination) (% germination) Cont. Inv. Cont. Inv. Cont.Inv. “Roc Yellow” 75 89 16 79 30 84 “Roc Golden” 76 83 36 86 26 75 “RocBlue” 55 72  8 74  5 70 “Roc White” 61 89  3 85  2 79 Cont. = controlprimed seeds dried Inv. = seed of invention

The results in the above table show the loss of viability during storageat 18° C. of conventionally primed seeds is much faster than that ofseeds of the invention. Thus the viability of conventionally primedseeds drops between 9 and 14 months, whereas seeds of the inventionremain viable for a period of longer than 23 months i.e for at leasttwice as long a period than conventionally primed seeds.

EXAMPLE 2 Slow Drying

60 g dry pre-treated seeds of Capsicum (pepper) are subjected to drumpriming as in Example 1, except that during priming MC is maintained at37% wet weight of the seeds. Thus a sufficient amount of water is addedto bring the seed MC up to 37%.

10 g (wet weight) control seeds are removed from the drum after 3 daysand dried as in the seeds control of Example 1 to a seed MC of 7%.

70 g thus primed seeds of a test sample (MC 37%) are subjected toincubation as in Example 1. in which the rate of moisture loss is 0,4%MC/hr. Seeds are then dried to a MC of 7%, under the same conditions asfor control seeds of Example 1. Shelf life is determined by subjectingthe seeds to a CD test as in Example 1 except that the seeds areincubated at 49° C. for 24 and 48 h. The results are shown in Table 2below.

TABLE 2 Shelf life of conventionally primed pepper seeds compared withprimed pepper seeds of the invention. The average t₅₀ before priming is4.6 days, after both treatments i.e. standard priming and slow dryingt₅₀ is 1.3 days. % normal plants after CD-test period (h) 0 24 48Standard Priming lot 1 86 63  4 lot 2 96 70  2 Slow Diying lot 1 84 8257 lot 2 94 92 72

EXAMPLE 3 Slow Drying

60 g dry seeds of Capsicum (pepper) are subjected to the steps describedin Example 2, with a minor difference in the rate of moisture loss.There it is 0,3% MC/hr. Seeds are then taken out of the drum and driedto a MC of 7% under the same conditions as for control seeds.

Control seeds (conventionally primed seeds) and seeds of the inventionare stored in air-tight aluminum-foil bags al 20° C. for 8 months.

Seeds are sown on water-saturated filter paper, and incubated at 20° C.in the light. The percentage of germinated seeds is counted daily, andthe mean time to germination calculated as in Example 1.

Shelf life is determined employing a CD test as in Example 1, exceptthat the seeds were incubated at 50° C.

% normal plants in soil is determined as described in Example 1.

The table shows that seeds of the invention survive both CD-conditionsand normal storage conditions to a much larger extent than controlseeds.

TABLE 3 Shelf life of conventionally primed pepper seeds compared withprimed seeds of the invention. t₅₀ before priming is 3.0 days, afterboth treatments t₅₀ is 0.7 days. % normal plants after % normal plantsin soil test CD test, period (hrs): after storage period (months): 0 240 8 Standard priming 99  4 81 15 Slow drying 98 94 84 88

EXAMPLE 4 Slow Drying

60 g dry seeds of Tomato are subjected to a drum priming as in Example1, except that the length of priming is 7 days and seed MC during theincubation is maintained at 38% wet weight of the seeds. Thus asufficient amount of water is added to bring the seed MC up to 38%.

10 g (wet weight) control seeds are removed from the drum after 7 daysand dried as for the control seeds of Example 1, to a MC of 6%.

70 g thus primed seeds of a test sample (MC 38%) are subjected to anincubation as in Example 1 in which the rate of water loss is 0.1-0.3%MC/hr. Seeds are then dried to a M.C. of 6%, under the same conditionsas for control seeds of Example 1.

Seeds are sown on water-saturated filter paper, and incubated at 20° C.in the light. The percentage of germinated seeds is counted daily, themean time to germination is calculated as in Example 1.

Shelf life is determined employing a CD test as in Example 1, exceptthat the seeds were incubated at 50° C. for 24 h-, 48 h- and 72 h.Resultd are shown in Table 4.

TABLE 4 Shelf life of conventionally primed tomato seeds compared withtomato seeds primed according to the invention. Average t₅₀ beforepriming is 4.0 days, after both treatments it is 1.5 days. % normalplants in paper test CD test period Standard priming Slow Drying (hours)lot 1 lot 2 lot 1 lot 2  0 87 92 93 92 24 84 90 92 90 48  7 36 69 86 72 2  7 37 69

EXAMPLE 5 Slow Drying

1200 g dry seeds of Cauliflower cv. Serrano are subjected to a drumpriming as in Example 1, except that during priming, the roomtemperature is controlled at 15° C. and seed MC is kept at 35%.

10 g (wet weight) control are removed from the drum after 7 days anddried as for the control seed of Example 1, to a MC of 6%.

100 g seeds of a test sample (MC 35%), are subjected to incubation in a6 liter drum for 5 days, in a wherein the room temperature is controlledat 20° C. and the room RH is controlled at 75%. The drum opening iscovered with a nylon mesh having a pore size of approx. 0,6 mm tofacilitate evaporation. Rate of water loss during the first day (0.62%MC/hr) is determined by weighing as described above. Seeds are thentaken out of the drum and dried under the same conditions as for controlseeds.

Shelf life is determined employing a CD test as in Example 1, exceptthat the seeds were incubated at 48° C. for 48 h.

Table 5 shows that a period of incubation that enables a slow reductionin seed MC strongly improves the shelf life of primed seeds, up to theshelf life of non-primed i.e. untreated seeds.

TABLE 5 % normal plants in paper test CD test period (relative tocontrol at start of CD test) (hours) Control (not primed) Standardpriming Slow Drying  0 100 94 94 48  60 27 60

EXAMPLE 6 Slow Drying

1200 g dry seeds of carrot cv. Autumn king Trophy are subjected to adrum priming for 6 days, under the priming conditions as in Example 5,seed MC during priming being maintained at 38% wet weight of the seeds.Rate of moisture loss (1-2% per day calculated on a fresh weight basis)is monitored daily by weighing the drum and contents each day andreplenishing with water each day to make up the weight differencesobserved between weighing.

10 g (wet weight) control seeds are removed from the drum after 7 daysand dried as for control seeds of Example 1, to a MC of 6%.

100 g seeds of a test sample are subjected to incubation for 5 daysunder the same incubation conditions as Example 5. Rate of water lossduring the first day (0.67% M.C h⁻¹) being determined as abovedescribed. Seeds are removed from the drum and dried as for controlseeds.

Shelf life is determined employing a CD test as in Example 1, exceptthat the seeds were incubated at 48° C. for 24 and 48 h.

Table 6 shows that a period of incubation which enables a slow reductionin seed MC, strongly improves the shelf life of primed carrot seeds.

TABLE 6 % normal plants in paper test CD test period (relative tocontrol at start of CD test) (hours) Control (not primed) Standardpriming Slow Drying  0 100  94 94 24 85 71 97 48 71 13 64

EXAMPLE 7 Slow Drying

1200 g dry seeds of Chicory witloof cv. Liberty are subjected to drumpriming as in Example 1, except that seed MC is maintained at 38% wetweight of the seeds.

10 g (wet weight) control seeds are removed from the drum after 7 daysand dried as for the control seeds in Example 1, to 6% MC.

450 g seeds of a test sample are subjected to incubation in a 24 literdrum for 5 days, in a room wherein the room temperature is controlled at20° C. and the room RH is controlled at 75%. The drum opening is coveredwith a cotton cloth having a pore size of approx. 0,1 mm to facilitateevaporation. Rate of water loss during the first day (0.29% MC/hr) isdetermined by weighing as described above. Seeds are then taken out ofthe drum and under the same conditions as for control seeds.

Shelf life is determined employing a CD test as in Example 1, exceptthat the seeds were incubated at 50° C. for 24 h.

Table 7 shows that a period of incubation that enables a slow reductionin seed MC strongly improves the shelf life of primed witloof seeds, upto the level of non-primed seeds.

TABLE 7 % normal plants in paper test CD test period (relative tocontrol at start of CD test) (hours) Control (not primed) Standardpriming Slow Drying  0 100 88 95 24  56  3 54

EXAMPLE 8 Slow Drying

1200 g dry seeds of Leek cv. Latina are primed for 4 days under thepriming conditions of Example 5. 0.01 g/kg seed Aatopam is added to theseeds. Seed MC during the priming is maintained at 38% wet weight of theseeds.

10 g (wet weight) control seeds are removed from the drum after 7 daysand dried as for the control seeds in Example 1, to 6% MC.

200 g seeds of a test sample are subjected to incubation in a 24 literdrum for 5 days, in a room wherein the room temperature is controlled at20° C. and the room RH is controlled at 40%. The drum opening is coveredwith a nylon mesh having a pore size of approx. 0,6 mm to facilitateevaporation. Rate of water loss during the first day (1.04% MC/hr) isdetermined by weighing as described above. Seeds are then taken out ofthe drum and dried under the same conditions as for control seeds.

Shelf life is determined employing a CD test as in Example 1, exceptthat the seeds were incubated at 48° C. for 24, 48 and 72 h.

Table 8 shows that a period of incubation that enables a slow reductionin seed MC strongly improves the shelf life of primed leek seeds, up tothe level of non-primed seeds.

TABLE 8 % normal plants in paper test CD test period (relative tocontrol at start of CD test) (hours) Control (not primed) Standardpriming Slow Drying  0 100 96 92 24 — 90 91 48 — 65 91 72 —  9 54

EXAMPLE 9 Moist Storage

Pansy seeds are pretreated and primed as described in Example 1.

10 g control seeds are removed from the drum after 3 days and dried asfor control of Example 1 to 6%.

10 g Seeds of a test sample (MC 34%) are dried as control seeds but to aMC of 25%.

The seeds are then transferred to a moisture-tight but not air-tightplastic container and incubated at 20° C. for 3 days. After thisincubation, the seeds are further dried similar to the control seeds.

Shelf life of the control (conventional priming), the seed of theinvention(moist storage) and untreated seed(i.e. not primed), isdetermined as described in example 1.

Table 9 shows the survival of conventionally primed seeds and seeds ofthe invention, after the 24 hrs CD test, expressed as a relative valuecompared to untreated seeds. The table shows that an incubation at areduced but constant seed MC (as compared to the seed MC after priming)reinstates shelf life in primed seeds.

TABLE 9 CD-test data (relative to untreated seed) of Pansy seeds thathave been conventionally drum-primed or treated according to theinvention (moist storage). CD test value (24 h) Untreated 100  Control(conventionally primed) 20 Seeds of invention (moist storage) 62

EXAMPLE 10 Moist Storage

100 g dry seeds of Capsicum (pepper)cv. Abdera are drum-primed as inexample 3.

The seed MC after priming was 35.3%. In 165 minutes the seeds were driedto a MC of 4.8% at a temperature of 25° C. 40% R.H. and an air speed of2 ms⁻¹. Two replicate seed samples were taken at MCs of 35.3 (initialMC), 30.6%, 25.5%, 20.0%, 14.8%, and 9.6%.

These samples were incubated in a closed container (0.15 dl), one sampleat 8° C., and the other at 20° C., for a period of 7 days.

After the incubations, all samples were dried to an end MC of 4.8% ,under similar conditions as the first drying step.

Shelf life of the control (conventionally primed), the seed of theinvention(moist storage) and untreated seed (i.e. not primed), isdetermined as described in example 1.

Table 10 shows that primed seeds dried back immediately after priming,to a MC of 4.8%, have a low survival after the CD test, while seedsincubated at a MC that is reduced with 5 to 15% as compared to the MCafter priming, have a shelf life that is almost similar to untreatedcontrol seeds.

The temperature during this induction step is not critical to theprocess.

TABLE 10 Effect of incubation of primed seeds at different seed MC at atemperature of 8° C. and 20° C. for a period of 7 days at 100% R. H. onCD-test survival. CD-test results (24 h) % normal plants Incubation at8° C. Incubation at 20° C. Control (untreated) 75 75 Control(conventionally 12  4 primed) Incubation at 35.3% MC 30 34 Incubation at30.6% MC 64 60 Incubation at 25.5% MC 54 84 Incubation at 20.0% MC 22 52Incubation at 14.8% MC  9 26 Incubation at 9.6% MC 14  4

EXAMPLE 11 Moist Storage

Tomato seeds are primed as in Example 4, for 6 days seed MC beingmaintained at 37.1%.

10 g control seeds are removed from the drum after 6 days and dried asfor control seeds of Example 1, to 6%.

10 g Seeds of a test sample (MC 37.1%) are dried as control seeds but toa MC of 25%.

The seeds are then transferred to a moisture-tight but not air-tightplastic container and incubated at 20° C. for 3 days. After thisincubation, the seeds are further dried as for the control seeds.

Germination rate and shelf life is determined as described in example 4.The control seeds had a t₅₀ of 4.4 days, the seeds treated according tothe invention, had a t₅₀ of 1.5 days.

Table 11 shows the survival after employing a CD test as in Example 1,except that the seeds were incubated at 50° C. for 48 hrs, expressed asa relative value compared to untreated control seeds. The table showsthat an incubation at a reduced, but constant seed MC i.e. moist storage(as compared to the seed MC after priming) reinstates shelf life inconventionally primed tomato seeds.

TABLE 11 CD-test data (relative to untreated seed) of tomato seeds thathave been conventionally drum-primed or treated according to theinvention (moist storage). CD test value (48 h) Control (Untreated) 100Control (conventionally primed) 6 Seeds of invention (Moist storage) 64

EXAMPLE 12 Heat Storage

100 g dry seeds of Capsicum (pepper)cv. Abdera are primed as in Example3.

The seed MC after priming was 35.3%. In 165 minutes the seeds were driedto a MC of 4.8% at a temperature of 25° C., 40% R.H. and an air speed of2 m.s⁻¹. Seed samples were taken at MCs of 35.3 (initial MC), 30.6%,20.0%. 14.8%, and 9.6%. These samples were incubated in a sealedaluminum bag in a waterbath at a temperature of 40° C. for a period ofthree hours.

After the incubations, all samples were dried to an end MC of 4.8% undersimilar conditions as the first drying step.

Shelf life of the control (conventional priming), the seed of theinvention(moist storage) and untreated seed(i.e. not primed), isdetermined as described in example 1.

Table 12 shows that primed seeds dried back immediately after thetreatment to a MC of 4.8% have a low survival after the CD test, whileseeds that were given a heat shock survived the CD test much better. Theheat shock was effective down to a seed MC of 15%.

TABLE 12 Effect of a heat shock on CD-test survival of primed pepperseeds. CD-test results % normal plants Control (untreated) 75 Control(conventionally primed) 14 Incubation at 35.3% MC 62 Incubation at 30.6%MC 46 Incubation at 20.0% MC 44 Incubation at 14.8% MC 46 Incubation at9.6% MC 24

EXAMPLE 13 PEG Treatment

10 gram Pepper cv. Abdera seeds are incubated on water-saturated filterpaper in transparent plastic boxes at 25° C. in light.

Seed samples of 1 gram are removed every day until day 4. At day 4, 40%of the seeds had germinated, whilst at day 3, no germinated seeds wereobserved. Control seed samples were dried according to example 1. Testsamples were transferred to filter paper saturated with a solution ofpolyethylene glycol with an osmotic potential of −1.5 MPa and incubatedfor 3 days at a temperature of 25° C. After the treatment, the seedswere washed and dried as for the control seeds.

Shelf life is determined employing a CD test as in Example 1.

Table 13 shows that seeds incubated in water for 1 day, have a somewhatenhanced shelflife, but incubation for 2 and 3 days show a progressiveloss of shelf life, whereas in comparison, seeds of the invention (whichhave been incubated in PEG solution) demonstrate a prolonged shelf-life.

TABLE 13 Length of CD test result (24 h) CD test result (24 h)incubation days control seeds seeds of invention 0 84 82 1 92 97 2 71 913  7 57

EXAMPLE 14 Combination of Water Stress and Heat Stress

50 g dry seed of Viola (Roc Yellow) are primed as described inExample 1. After three days of priming seeds are transferred to aeratedwater at a temperature of 20° C. After 24 h in aerated water themajority of the seeds show splitting of the seed coat, but the radiclehas not yet broken through the enveloping endosperm. The seeds are thenremoved from the water and centrifuged. The seed MC is 48.5%.

5 g (wet weight) of these seeds, is dried by exposure at 20° C., tostill air having a R.H. of 40%. After 24 h of drying the MC of the seedsis 6%. The remainder of the seeds is divided into three portions, eachof which is exposed to air flowing at 2ms⁻¹ at a temperature of 20° C.and a RH of 40%. Seeds are exposed to the flowing air for severalminutes until the three portions have reached MCs of 40, 35 and 30%.respectively. Two samples of 10 g are taken from each portion and packedin minimal moisture and air exchange plastic containers (180 ml) andthereafter incubated at temperatures of either 20° C. or 32° C. After 1and 7 days incubation at the temperatures indicated, 2 g of each sampleis dried under the same conditions as the seeds which were not incubatedbefore drying, as above described.

Shelf life of the treated dried seed is determined using CD-testssimilar to those described in Example 1, the seeds being in equilibriumat a R.H. of 40% being incubated at 50° C. for 96 h and germinated onpaper at 20° C., as described in Example 1.

Final germination percentage is counted after 14 days; the resultsbelow, show % germination in the absence of a CD-test control and aftera CD-test (96 h).

TABLE 14 Germination percentage of primed viola seeds before and afterCD tests after different incubation treatments. Germination % CD-testIncubation Treatment (control) (96 h) Time (day) Temp. Moisture NoCD-test Germination % 0 — 48.5 87 34 1 20 40 86 49 1 20 35 86 69 1 20 3082 75 1 32 40 81 68 1 32 35 84 87 1 32 30 82 69 7 20 40 85 64 7 20 35 8876 7 20 30 82 78 7 32 40 82 92 7 32 35 89 79 7 32 30 89 83

What is claimed is:
 1. A method for prolonging the shelf life of primed non-germinated seeds comprising the steps of: a) priming seeds; b) treating the primed seeds to an incubation wherein said incubation includes incubating the primed seeds at a temperature range of about 3 to about 40° C. for a period of about 1 to about 7 days; c) obtaining treated incubated primed seeds wherein the treated seeds have a moisture content of between about 3 to 20% units lower than the moisture content of untreated primed seeds of the same plant species; and d) drying the treated incubated primed seeds to substantially the moisture content of non-incubated non-primed seeds of the same plant species wherein the treated incubated seeds have a prolonged shelf life without loss of viability as compared to the viability of primed non-incubated seeds of the same plant species.
 2. The method according to claim 1 wherein the drying step d) is at temperature range of 10 to 50° C. for not more than about 24 hours.
 3. The method according to claim 1 wherein the moisture content of the dried treated incubated primed seeds is between 2 and 15% on a fresh weight basis.
 4. The method according to claim 1 wherein the moisture content of the treated incubated primed seeds of step c) is between 15 and 55%.
 5. The method according to claim 1 wherein the moisture loss during the incubation step is in the range of about 0.2 to about 0.4% per hour.
 6. The method according to claim 1 wherein the treating step b) is at a temperature range between about 20 to about 35° C.
 7. The treated incubated primed seeds obtained according to the method of claim
 1. 8. The treated incubated primed seeds obtained according to the method of claim
 3. 9. The treated incubated primed seeds of claim 7 wherein the seeds are selected from the group consisting of tomatoes, peppers, melons, watermelons, cucumbers, Brassicas, leeks, carrots, onions, squashes, gerkins, endives, Impatiens, Verbenas, Primulas, Pelargoniums, Violas, Cichoriums and Cyclamen.
 10. The treated incubated primed seeds obtained according to the method of claim 1 wherein said seeds are pepper seeds.
 11. The treated incubated primed seeds obtained according to the method of claim 1 wherein said seeds are tomato seeds.
 12. The method according to claim 1 wherein the treating step b) further comprises subjecting the primed seeds to a heat shock in the temperature range between about 25 to 45° C. for about 1 to 5 hours.
 13. The method according to claim 1 further comprising the step of providing a protective coating on the treated incubated primed seeds.
 14. The method according to claim 1 further comprising the step of storing the treated primed seeds at a temperature range between about 3 to 25° C. and at a relative humidity in the range of 20 to 90%.
 15. The stored treated seeds obtained according to the method of claim 14 wherein the shelf life is at least 35% longer than the shelf life of untreated primed seeds of the same plant species and having substantially the same moisture content.
 16. The method according to claim 14 wherein said treated seeds are stored between 8 and 24 months.
 17. The stored treated seeds obtained according to the method of claim 14 wherein said treated seeds have a t₅₀ which is 60% or less than that of untreated non-primed seeds of the same species.
 18. A method for prolonging the shelf life of primed non-germinated seeds comprising the steps of: a) priming seeds; b) treating the primed seeds to an incubation wherein said incubation is selected from the group consisting of (i) incubating the primed seeds in the temperature range from between about 3 to about 40° C. for a period of about 1 to about 7 days; (ii) incubating the primed seeds in an osmoticum for 1 to 7 days at a water potential in the range of from −0.5 to about −4.0 MPa; (iii) reducing the moisture content of the primed seeds by 3 to 20% units lower than the moisture content of untreated primed seeds of the same plant species at a temperature range of between 3 to about 25° C. for not more than 24 hours and storing the seeds for about 1 to 7 days in a container with minimal air and moisture exchange at a temperature from about 3 to 40° C.; and (iv) a combination of i) or ii) or iii) above; c) obtaining treated incubated primed seeds wherein the treated seeds have a moisture content about 3 to 20% units lower than the moisture content of untreated primed seeds of the same plant species; and d) drying the treated seeds to a moisture content of untreated seeds of the same plant species wherein the treated seeds have a prolonged shelf life without loss of viability as compared to the viability of untreated primed seeds of the same plant species.
 19. The method according to claim 18 wherein the treating step b) further comprises subjecting the primed seeds to a heat shock in the temperature range of from 25 to 45° C. for about 1 to 5 hours.
 20. The method according to claim 18 wherein the moisture content of the dried treated seeds is between 2 to 15% on a fresh weight basis.
 21. The method according to claim 18 further comprising the step of storing the dried treated primed seed at a temperature range of between about 3 to 25° C. and a relative humidity in the range of 20 to 90%.
 22. The treated incubated primed seed obtained according to the method of claim
 18. 23. A method for prolonging the shelf life of primed non-germinated seeds comprising the steps a) priming seeds; b) treating the primed seeds to a heat shock in the temperature range of from 25 to 45° C. for about 1 to 5 hours; c) obtaining treated primed seeds wherein the treated seeds have a moisture content about 0 to 20% units lower than the moisture content of untreated primed seeds of the same plant species; and e) drying the treated seeds to a moisture content of untreated seeds of the same plant species wherein the treated seeds have a prolonged shelf life without loss of viability as compared to the viability of untreated primed seeds of the same plant species.
 24. In a method of priming seeds the improvement comprising: treating non-germinated seeds after imbibition, but prior to drying to a moisture content of untreated nonprimed seeds, to an incubation wherein said incubation includes a heat stress, water stress or combination thereof and wherein the shelf life of the incubated primed non-germinated seeds is extended compared to untreated primed non-germinated seeds of the same species.
 25. The method according to claim 24 wherein the water stress includes incubating the imbibed seeds at a temperature range of between about 3 to about 40° C. for a period of about 1 to about 7 days.
 26. The method according to claim 1 further comprising the step of adding a beneficial biological to the treated incubated primed seed.
 27. The treated incubated primed seeds obtained according to claim
 26. 